Theresa May, the Home Secretary, will today face questioning by MPs over Government plans to introduce an unprecedented level of surveillance of mobile phones and internet use in what has been derided as a snoopers' charter.

The plans are expected to be announced in the Queen's Speech in May and are likely to include provisions to allow the security services access to every piece of internet traffic in the United Kingdom, on demand. This would mean that Government agents would be allowed to see what websites people are accessing, and for how long. They would also be able to see who was emailing whom, who was phoning whom, and for how long.